Nerve sheath tumor malignant peripheral C47.-

Group of malignant neurogenic tumors (MPNST) originating from peripheral nerves or showing nerve sheath differentiation. Occurring in approximately 2-5% in peripheral neurofibromatosis (NF type I), de novo origin and malignant transformation of a preexisting neurofibroma are discussed. MPNST can also occur in pre-irradiated body parts after decades of latency. Molecularly, 17q and 9p deletions are encountered.

In case of spontaneous emergence no gender preference; in this case the first manifestation age is >50 years. In connection with neurofibromatosis, malignancy development occurs earlier (35-40 years), in this collective men are preferentially affected.

Head and neck, extremities, trunk

Variably sized, rapidly growing, deeply cutaneous or palpable as a subcutaneous mass, painless also painful, solid nodule. The tumour may develop de novo (rather rarely) or in the context of neurofibromatosis from a long-known neurofibroma.

Large, blurred, cutaneous-subcutaneous localized tumor formations consisting of densely packed spindle-shaped cells with wavy or comma-shaped nuclei. Rarely palisade formations with Meissner`s corpuscles. Pronounced cell and nuclear atypia, abundant mitoses, many immature fibroblasts, fine argyrophilic neurofibrils. Immunohistochemistry shows positivity for S100 and p53 protein.

Rare variants of the tumor are:

• Epithelioid malignant peripheral nerve sheath tumor (epithelioid cell component).
• Glandular malignant peripheral nerve sheath tumor (glandular structures).
• Malignant triton tumor(rhabdomyosarcomatous differentiation )

High recurrence rate even with sufficient excision. 5-year survival rate is 50% for sporadic tumors; 5-year survival rate for underlying neurofibromatosis 20-25%.

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